Reversible upconversion luminescence modification based on photochromism has received considerable interest due to its potential applications in optical storage and high‐sensitivity optical switches. However, stimulation‐induced bleaching by an external thermal field is generally used for photochromism‐induced reversible upconversion luminescence modification, which limits its practical application. In this work, a gray BaMgSiO4:Yb3+,Tb3+ ceramic is prepared, exhibiting the photochromism from gray to pink color when stimulated by 254 nm light. Interestingly, the pink BaMgSiO4:Yb3+,Tb3+ ceramic can be bleached by either a 473 nm laser or thermal stimulation. The reversible change between gray and pink color exhibits excellent reproducibility over several cycles by alternating between 254 and 473 nm (or thermal) light stimulation. The influence of the reversible photochromism of the BaMgSiO4:Yb3+,Tb3+ ceramic on its upconversion luminescence is investigated. Reversible modification of the upconversion luminescence is demonstrated by alternating between 254 and 473 nm (or thermal) light stimulation. For reversible modulation of the upconversion luminescence, excellent reproducibility is realized after several cycles. As an example, the application of the BaMgSiO4:Yb3+,Tb3+ photochromic ceramic as an anti‐counterfeiting agent is described.
Visible-light persistent phosphors are commonly used as self-sustained night vision and fluorescence labeling materials. From the inspiration of the structure of six-membered rings plane in Ba4(Si3O8)2, a similar structure of Ba5Si8O21 is expected that could exhibit more excellent phosphorescence property. In this Article, we report a novel visible long-lasting luminescence phosphor of Eu(2+)/Dy(3+) codoped Ba5Si8O21 for the first time. Ba5Si8O21:Eu(2+),Dy(3+) phosphor could be activated effectively by sunlight or even in severe weather conditions, which is mainly attributed to the broad excitation spectrum (200-455 nm) and highly responds to UV-A and violet-light in the solar spectrum. After activation, Ba5Si8O21:Eu(2+),Dy(3+) emits intense emission at 380-680 nm with persistent phosphorescence beyond 16 h. Moreover, it exhibits excellent and stable phosphorescence even in water, indicating that Ba5Si8O21:Eu(2+),Dy(3+) will be a all-weather material that can be effectively and repeatedly charged by natural daylight in all kinds of open-air environments. Furthermore, the quantum tunneling behavior was illustrated in the afterglow mechanism.
All-inorganic perovskites of CsPbBr 3 nanocrystals (NCs) exhibit strong X-ray absorption and have been demonstrated to be highly efficient scintillators for X-ray detection and imaging. However, the long-term stability of the perovskite remains a major hurdle in practical applications, especially under a commercial dose of X-ray irradiation (0.5−5.5 mGy• s −1 ). Herein, with a solution-protected annealing approach reconstructing the CsPbBr 3 NCs free from undesired defects, the perovskite scintillators provide a long-term (∼3600 s) stable visualization tool for X-ray radiography (1.44 × 10 6 captured images for the exposure time of 2.5 ms per image) under the irradiation dose of 1 mGy•s −1 . This work opens a window for the stability of perovskite scintillators and demonstrates their robust and long-term efficient radioluminescence (RL) for low-cost radiography and X-ray imaging application.
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